[css-grid] Consider invalid using just "span" as grid-line value

third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-item-column-row-get-set.html

Index: third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-item-column-row-get-set.html
diff --git a/third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-item-column-row-get-set.html b/third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-item-column-row-get-set.html
index acf54073993869d04c2ee409630644747f11b4ef..066bfc81f2327ba1612ef845c490d50270f8e87d 100644
--- a/third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-item-column-row-get-set.html
+++ b/third_party/WebKit/LayoutTests/fast/css-grid-layout/grid-item-column-row-get-set.html
@@ -76,7 +76,7 @@
     grid-row: firstArea;
 }
 .gridItemWithNamedGridAreaAndSpan {
-    grid-column: thirdArea / span;
+    grid-column: thirdArea / span 1;
     grid-row: firstArea / span 2;
 }
 </style>
@@ -116,7 +116,7 @@
     testColumnRowCSSParsing("gridItemWith2IntegerElement", "10 / 15", "5 / 5");
     testColumnRowCSSParsing("gridItemWithNegativePositiveIntegerElement", "10 / -10", "-8 / 5");
     testColumnRowCSSParsing("gridItemWithBeforeSpanElement", "span 2 / 4", "3 / span 5");
-    testColumnRowCSSParsing("gridItemWith2OnlySpanElement", "span 1 / span 1", "span 1 / span 1");
+    testColumnRowCSSParsing("gridItemWith2OnlySpanElement", "auto / auto", "auto / auto");
     testColumnRowCSSParsing("gridItemWith2AutoElement", "auto / auto" , "auto / auto");
     testColumnRowCSSParsing("gridItemWithBothShortLongHandElement", "10 / 11", "4 / 5");
     testColumnRowCSSParsing("gridItemWithNoSpaceElement", "auto / 1", "5 / auto");
@@ -148,7 +148,8 @@
     testColumnRowJSParsing("-5 / 5", "4 / -4");
     testColumnRowJSParsing("4 / auto", "5 / auto");
     testColumnRowJSParsing("auto / 5", "auto / 8");
-    testColumnRowJSParsing("span / 3", "5 / span", "span 1 / 3", "5 / span 1");
+    testColumnRowJSParsing("span / 3", "5 / span", "auto / auto", "auto / auto");
+    testColumnRowJSParsing("span 1 / 3", "5 / span 1", "span 1 / 3", "5 / span 1");
     testColumnRowJSParsing("first span / 3", "5 / last span", "span 1 first / 3", "5 / span 1 last");
     testColumnRowJSParsing("first / last", "nav / last span", "first / last", "nav / span 1 last");
     testColumnRowJSParsing("3 first / 2 last", "5 nav / last 7 span", "3 first / 2 last", "5 nav / span 7 last");
@@ -201,6 +202,10 @@
     testColumnRowInvalidJSParsing("6 / 0", "8 / 0");
     testColumnRowInvalidJSParsing("0", "0");
 
+    // 'span' alone is invalid
+    testColumnRowInvalidJSParsing("span", "span");
+    testColumnRowInvalidJSParsing("span / span", "span / span");
+
     // 'span' and 'auto' are not valid <custom-ident>
     testColumnRowInvalidJSParsing("span span / span span", "span span / span span");
     testColumnRowInvalidJSParsing("span auto / span auto", "span auto / span auto");